Guide pin for optical fiber connectors and optical fiber connector plug

ABSTRACT

The guide pin (P) in accordance with the present invention is a guide pin (P) having a predetermined pin diameter to be inserted into a guide pin insertion hole ( 9 ) of a ferrule ( 11 ); which is configured to have an inserting portion ( 31 ) penetrating through the ferrule ( 11 ), and an engagement portion ( 32 ), having a diameter greater than that of the guide pin insertion hole ( 9 ), adapted to abut against the back face ( 11   b ) of the ferrule ( 11 ).

TECHNICAL FIELD

The present invention relates to an optical connector guide pin to beutilized for coupling optical connector plugs to each other upon opticalinterconnection, and an optical connector plug having such a guide pin.

BACKGROUND ART

Conventionally, as a technique in such a field, Japanese PatentApplication Laid-Open No. HEI 6-34845 has been known. The opticalconnector plug disclosed in this publication has a ferrule of arectangular parallelepiped form, and an optical fiber exposed from a tipof a ribbon fiber is fixed to this ferrule. Also, the ferrule has twoguide pin insertion holes each extending in the optical fiber insertiondirection and penetrating therethrough from the front face to the backface, while a guide pin is inserted in each guide pin insertion hole.Further, the optical connector plug has a damper disposed behind theferrule, which prevents the guide pin from dropping out of the ferrule.Specifically, the rear end part of each guide pin is formed with aconstricted portion, which is fitted into an insertion hole formedbetween engagement lugs of the clamper, thereby preventing the guide pinfrom dropping out. Also,when the optical connector plug is used in aplace where the guide pin is strongly desired to be prevented fromdropping out, the guide pin and the damper are secured with an adhesive.

However, since the conventional optical connector plugs are configuredas mentioned above, there have been problems as follows. Namely, inorder to prevent the guide pin from easily dropping out of the ferrule,the guide pins and the damper have been machined into complicated forms,and it has been necessary to strictly manage the dimensions of theconstricted portion of the guide pin and the insertion hole in thedamper in order to maintain the clamping force of the damper withrespect to the guide pin. Also, when the guide pin is strongly desiredto be prevented from dropping out, the guide pin has been secured withan adhesive, thus increasing the cost. Further, when inserting the guidepin into the guide pin insertion hole of the ferrule, if the guide pinis inserted from the front face side of the ferrule, there has been apossibility that the tip of the guide pin may damage the front face ofthe ferrule, thereby deteriorating the quality of the ferrule.

In order to overcome the above-mentioned problems, it is an object ofthe present invention to provide a guide pin and an optical connectorplug which facilitate simplification of the structure, make it possibleto cut down the cost, and contribute to maintaining the quality of theferrule.

DISCLOSURE OF THE INVENTION

The optical connector guide pin in accordance with the present inventionis an optical connector guide pin having a predetermined pin diameter tobe inserted into a guide pin insertion hole of a ferrule; wherein theguide pin comprises an inserting portion penetrating through theferrule, and an engagement portion, having a diameter greater than thatof the guide pin insertion hole, adapted to abut against a back face ofthe ferrule.

Since the rear end part of the guide pin is provided with the engagementportion formed greater than the guide pin insertion hole; when the guidepin is attached to the ferrule, the engagement portion can prevent theguide pin from forwardly dropping out. Also, when such a guide pin is tobe projected from the front face of the ferrule by a predeterminedamount, the tip of the guide pin would be inserted into the guide pininsertion hole from the back face side of the ferrule. Namely, thisguide pin is not expected to be inserted from the front face side of theferrule, whereby the tip of the guide pin would not damage the frontface of the ferrule nor chip off the guide pin hole during the operationof inserting the guide pin into the ferrule. Also, changing the positionof the engagement portion can easily alter the amount of projection ofthe tip portion of the guide pin from the ferrule.

An optical connector plug in accordance with the present invention is anoptical connector plug comprising a ferrule having there with in anoptical fiber aligning portion for aligning a plurality of opticalfibers and guide pin insertion holes penetrating therethrough from afront face to a back face on both sides of the optical fiber aligningportion, in which the optical fibers are secured to the optical fiberaligning portion, and a guide pin is inserted in each guide pininsertion hole; wherein the guide pin has an inserting portionpenetrating through the ferrule, and an engagement portion, having adiameter greater than that of the guide pin insertion hole, adapted toabut against the back face of the ferrule.

In this optical connector plug, a simple operation of just inserting theguide pin into the guide pin insertion hole from the back face side ofthe ferrule can achieve positioning of the guide pin with respect to theferrule, thus contributing to improvement in the workability ofassembling.

An optical connector plug in accordance with the present invention is anoptical connector plug having a ferrule pressed outward by a springmember in a ferrule accommodating space disposed at a front end portionof a ferrule housing, so as to peep from an outlet opening of theferrule accommodating space, holding the ferrule in a floating statewithin the ferrule accommodating space, and projecting a tip portion ofa guide pin from a guide pin insertion hole formed in the ferrule;wherein the guide pin comprises an inserting portion penetrating throughthe ferrule, and an engagement portion, having a diameter greater thanthat of the guide pin insertion hole, adapted to abut against a backface of the ferrule, and wherein a stopper is disposed between theengagement portion and the spring member, the stopper abutting against arear end face of the guide pin while in a state separated from theferrule.

This optical connector plug has a configuration in which the springmember is utilized for outwardly pressing the ferrule. This is astructure for improving the connectivity between the end faces offerrules upon plugging by way of the guide pin. Also, as a stopper isdisposed between the ferrule and the spring member, the ferrule is keptfrom being directly pushed by the spring member, whereby the ferrule canappropriately be prevented from being broken or chipped off by thespring member. Further, the stopper inhibits the guide pin fromretracting. For example, when coupling ferrules to each other by way ofthe guide pin, the stopper inhibits the guide pin from retracting as itstip abuts against the front face of the opposed ferrule.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an embodiment of an opticalconnector to which an optical connector plug in accordance with thepresent invention is applied;

FIG. 2 is a sectional view of the optical connector plug shown in FIG.1, taken along the line II—II;

FIG. 3 is a sectional view of the optical connector plug shown in FIG.1, taken along the line III—III;

FIG. 4 is a partly cutaway sectional view of an adapter;

FIG. 5 is a partly cutaway sectional view showing a state where one ofoptical connector plugs is inserted into the adapter;

FIG. 6 is a partly cutaway sectional view showing a state where theother optical connector plug is in the process of being inserted intothe adapter;

FIG. 7 is a partly cutaway sectional view showing a state where both ofthe optical connector plugs are completely inserted into the adapter;

FIG. 8 is a sectional view showing a ferrule and a stopper which areutilized in the optical connector plug in accordance with the presentinvention;

FIG. 9 is a perspective view showing a state where the ferrule and thestopper are assembled together;

FIG. 10 is a perspective view showing a first embodiment of the guidepin in accordance with the present invention;

FIG. 11 is a plan view of the guide pin shown in FIG. 10;

FIG. 12 is a perspective view of the stopper shown in FIG. 9;

FIG. 13 is a plan view of the stopper shown in FIG. 12;

FIG. 14 is a front view of the stopper shown in FIG. 12;

FIG. 15 is a sectional view taken along the line XV—XV of FIG. 14;

FIG. 16 is a sectional view showing another embodiment of the opticalconnector to which the optical connector plug in accordance with thepresent invention is applied;

FIG. 17 is a perspective view showing a second embodiment of the guidepin in accordance with the present invention;

FIG. 18 is a perspective view showing a third embodiment of the guidepin in accordance with the present invention;

FIG. 19 is a perspective view showing a fourth embodiment of the guidepin in accordance with the present invention;

FIG. 20 is a plan view of the guide pin shown in FIG. 19; and

FIG. 21 is a sectional view showing a state where a ferrule and astopper which are utilized in the optical connector plug in accordancewith the present invention are separated from each other.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, preferred embodiments of the optical connector guidepin and optical connector plug in accordance with the present inventionwill be explained in detail with reference to the drawings.

FIG. 1 is a perspective view showing an optical connector. The opticalconnector 1 shown in this drawing is a push-pull type optical connector.Namely, just pushing a pair of optical connector plugs 2, 3 into anadapter 4 achieves plugging by way of the adapter 4 in a single motion.Also, the individual optical connector plugs 2, 3 can easily be takenout from the adapter 4 by pulling them out while pinching ejectors(knobs) 5, 5 provided in the optical connector plugs 2, 3 with fingers.In the following, structures of the individual optical connector plugs2, 3 and adapter 4 will be explained.

As shown in FIGS. 2 and 3, the optical connector plug 2 has asleeve-shaped housing 10, whereas a ferrule 11 made of a plastic isaccommodated within the housing 10. Specifically, a ferruleaccommodating space S having a rectangular cross section is formed at afront end portion of the housing 10, whereas a ferrule main body 12having a quadrangular prism form is accommodated within the ferruleaccommodating space S. Also, the rear end of the ferrule 11 is providedwith a projection 13, which has a front end face 13 a abutting against astepped abutment face 10 b formed in the inner wall face 10 a of thehousing 10.

Further, the optical connector plug 2 has a hollow holder 14 secured tothe rear end of the housing 10. In front of the holder 14, a stopper 15which will be explained later is disposed. The stopper 15 is caused toabut against the projection 13 of the ferrule 11, so that the stopper 15and the holder 14 are separated from each other, whereas a coil spring16, as a ferrule-pressing spring member, is disposed in the resultinggap. As a result, the ferrule is forwardly pressed due to the urgingforce of the spring 16, whereby the front end face 13 a of theprojection 13 of the ferrule 11 is pressed against the abutment face 10b provided in the inner wall face 10 a of the housing 10.

Hence, if the stepped abutment face 10 b is utilized as the referencesurface, then the positioning of the ferrule 11 is reliably achievedwithin the housing 10, and the ferrule 11 can securely be held with thehousing 10 while in a state where the front end portion of the ferrule11 slightly peeps from the outlet opening 17 of the ferruleaccommodating space S. Here, guide pins P are arranged within theirrespective guide pin holes 9 penetrating through the ferrule 11 in itslongitudinal direction (coupling direction), such that the tip of eachguide pin P projects from the connection end face (front face) 11 a ofthe ferrule 11.

Further, the optical connector plug 2 has the sleeve-shaped ejector 5located at the outer periphery of the housing 10 and holder 14, which isslidable in the longitudinal direction of the housing 10. The ejector 5is forwardly pressed by coil springs 1P for the ejector. Specifically,each coil spring 18 is disposed between a spring bearing 19 secured tothe outer peripheral face of the rear portion of the holder 14 and aprotrusion 5 a formed on the inner peripheral face of the ejector 5, andforwardly stresses the ejector 5.

Consequently, as the ejector 5 is moved back while being pinched withfingers, it retracts against the spring forces of the coil springs 18;and, when the fingers are released, the ejector 5 moves forward due tothe spring forces. In the vicinity of the tip of the ejector 5, theouter wall face 10 c of the housing 10 is formed with claw-engagingdepressions 20 for engaging claws 23 (see FIG. 4) of the adapter 4.

Here, optical fibers 8 having a plurality of cores (e.g., four cores)are embedded within a ribbon fiber 7, which extends from the rear end ofthe ferrule 11 through the optical connector plug 2 to the outside.Secured to a rear portion of the optical connector plug 2 is a boot 21,which protects the ribbon fiber 7.

As shown in FIG. 4, the adapter 4 for receiving thus configured opticalconnector plug 2 has a through hole 25 therewith in for inserting thehousing 10 of the optical connector plug 2, and the through hole 25 isformed with a protective cover 22 made of a plastic. On the inner wallface 22 a side of the protective cover 22, a pair of claws 23 having aspringiness extend over the whole length of the through hole 25 in acantilever state, whereas the tip of each claw 23 is formed with aprotrusion 24 adapted to engage the claw-engaging depression 20 of theoptical connector plug 2. The protrusions 24 are formed at both ends ofeach claw 23, since the optical connector plug 2 and the opticalconnector plug 3 (see FIG. 1) are expected to be inserted into thethrough hole 25 of the adapter 4 from both sides.

The coupling of the optical connector plug 2 and the optical connectorplug 3 by way of the above-mentioned adapter 4 will now be explainedbriefly. Since the optical connector plug 3 has substantially the sameconfiguration as that of the optical connector plug 2, they will beexplained with the same reference numerals or letters.

First, as shown in FIG. 5, the optical connector plug 2 is inserted intothe through hole 25 of the adapter 4 from one side thereof, so as to besecured to the adapter 4, thereby positioning the ferrule 11 of theoptical connector plug 2 within the adapter 4. Thereafter, as shown inFIG. 6, the optical connector plug 3 is inserted into the through hole25 of the adapter 4 from the other side, whereby the guide pins Pdisposed at the ferrule 11 of the connector plug 2 enter theircorresponding guide pin holes 9 formed in the ferrule 11 of the opticalconnector plug 3. Then, as the optical connector plug 3 is pushed intothe adapter 4, the respective end portions of the claws 23 keepretracting the ejector 5 against the spring forces of the coil springs18 while abutting against the ejector 5.

Thereafter, as shown in FIG. 7, at the same time when the protrusions 24disposed at the tips of the claws 23 enter their correspondingclaw-engaging depressions 20 of the optical connector plug 2, theejector 5 is released from the claws 23, so that the ejector 5 returnsdue to the spring forces of the coil springs 18, thereby pressing theprotrusions 24 of the claws 23 from there above. As a result, the claws23 of the adapter 4 and the housing 10 of the optical connector plug 3securely engage each other, thereby achieving dropout prevention for theoptical fiber plug 3 with respect to the adapter 4. At the same timewhen this dropout prevention is completed, an end-face junction betweenthe ferrule 11 of the optical connector plug 2 and the ferrule 11 of theoptical connector plug 3 is completed within the adapter 4.

An assembling operation similar to that mentioned above is also carriedout when inserting the optical connector plug 2 into the adapter 4. Whenremoving the optical connector plug 2 and the optical connector plug 3from the adapter 4, if they are pulled out while the ejectors (knobs) 5are pinched with fingers, then the pressing of the claws 23 by theejectors 5 is released, whereby the individual optical connector plugs2, 3 can easily be taken out from the adapter 4.

For smoothly connecting the optical connector plugs 2, 3 by way of theadapter. 4, each optical connector plug 2, 3 employs a floatingstructure in which the ferrule 11 can be moved within the housing 10.Namely, as shown in FIGS. 2 and 3, the ferrule 11 is accommodated in theferrule accommodating space S of the housing 10 with a predeterminedclearance C.

Here, as shown in FIGS. 8 and 9, the ferrule 11 is formed with two guidepin insertion holes 9 each having a borediameter of 700 μm, whereas aplurality of (e.g., four) optical fiber insertion holes 30, as anoptical fiber aligning portion, are formed between the two guide pininsertion holes 9 in parallel therewith. The optical fiber aligningportion may also be formed like a groove. The four optical fibers 8projecting from the tip portion of the ribbon fiber 7 are inserted intothe respective optical fiber insertion holes 30, whereas the guide pinsP made of SUS are inserted into the respective guide pin insertion holes9. The tip portion of each guide pin P projects from the connection endface (front face) 11 a of the ferrule 11 by a predetermined amount.

As shown in FIGS. 10 and 11, each guide pin P has a cylindricalinserting portion 31 with a pin diameter of 699 μm penetrating throughthe ferrule 11, whereas a rear end portion of the guide pin P is formedwith an engagement portion 32 for abutting against the back face 11 b ofthe ferrule 11. The engagement portion 32 comprises two fins 33 radiallyprojecting from the peripheral face of the guide pin P, each having aform which is a half of a circular cone divided into two along its axisof rotation, whereas each fin 33 radially projects beyond the pindiameter of the guide pin P. This engagement portion 32 is formed suchthat regions each having a length on the order of 1 to 2 mm in the rearend portion of the guide pin P project to both lateral sides from a flatportion which is flattened to a thickness of about 500 μm by pressing.Upon this pressing, an unshown press surface is formed with a depressionhaving substantially the same shape as that of the rear end portion ofthe guide pin P, by which the fins 33 each constituting the half of thecircular cone are integrally formed with the guide pin P on both side ofthe rear end portion. The front side of each fin 33 is formed with asubstantially semicircular positioning part 34 abutting against the backface 11 b of the ferrule 11, and the positioning part 34 is formed as asurface parallel to the back face 11 b of the ferrule 11.

Therefore, as shown in FIG. 8, when the guide pin P is attached to theferrule 11, the positioning part 34 of the fin 33 abuts against the backface 11 b of the ferrule 11, there by reliably preventing the guide pinP from forwardly dropping out. Also, when the guide pin P having such aform is loaded into the guide pin insertion hole 9 from the back face 11b side of the ferrule 11, the tip of the guide pin P would be insertedtherein. Namely, the guide pin P is not expected to be inserted into theferrule 11 from the front face 11 a side, whereby the tip of the guidepin P would not damage the front face 11 a of the ferrule 11 nor chipoff the guide pin hole 9 during the operation of inserting the guide pinP into the ferrule 11.

Also, as shown in FIGS. 10 and 11, a protrusion 50 b projecting rearwardfrom the fin 33 and a widened portion 50 a having a width W adapted toclosely engage the wall face of the guide pin insertion hole 9 betweenthe inserting portion 31 and the fin 33 are integrally formed with eachother in a flat form by pressing. As a consequence, when the width W ofthe widened portion 50 a is formed slightly greater than the guide pininsertion hole 9, and is pushed into the latter, it closely engages thewall face of the guide pin insertion hole 9, thereby appropriatelypreventing the guide pin P from rattling and from dropping out. Changingthe position of the fins 33 can easily alter the amount of projection ofthe guide pin P from the ferrule 11.

Here, the dropout strength of the guide pin P having the above-mentionedconfiguration was measured. Then, a guide pin secured to a ferrule by anadhesive alone as in a conventional case dropped out of the ferrule at aforce of about 1 kgf. By contrast, the guide pin P of the presentinvention did not drop out even when a force of 10-odd kgf was appliedthereto, whereby a very high dropout strength was experimentallyverified.

Thus configured guide pin P would also project from the back face 11 bside of the ferrule 11. Therefore, as shown in FIGS. 12 to 15, the frontface 15 a of the stopper 15 made of a resin is formed with a depression35 for accommodating the projecting portion 50 b of the guide pin Pprojecting from the back face 11 b of the ferrule 11. Also, the innerwall face of depression 35 is formed with a stopper surface 37 opposingto and abutting against the rear end face 36 of the guide pin P.Therefore, as the rear end face 36 of the guide pin P is pressed againstthe stopper surface 37, the guide pin P is appropriately inhibited fromretracting. It will be sufficient if the depression 35 has a simple dentform, and its form is not restricted in particular as long as it hassuch dimensions that the rear end portion of the guide pin P can beaccommodated therein.

Also, when the stopper 15 is caused to abut against the back face 11 bof the ferrule 11, the stopper surface 37 would abut against the rearend face 36 of the guide pin P (see FIG. 8). As a consequence, the guidepin P would not rattle in the axial direction of the guide pin insertionhole 9, and the position of the guide pin P with respect to the ferrule11 is always kept in a constant state even when a load is externallyapplied to the guide pin P. Formed at the center of the stopper 15 is aribbon fiber guiding groove 38 for rearwardly drawing out the ribbonfiber 7 secured to the ferrule 11.

Here, as shown in FIG. 21, the back face 11 b of the ferrule 11 and thefront face 15 a of the stopper 15 may be separated from each other byabout 0.1 mm. In this case, the rear end face 36 of the guide pin Pabuts against the stopper surface 37 of the depression 35 of the stopper15. As a result, the spring force of the coil spring 16 would notdirectly be transmitted to the ferrule 1, whereby it is possible toattain a configuration in which the spring force is indirectlytransmitted to the ferrule 11 by way of a pair of right and left guidepins P. Consequently, the spring force of the coil spring 16 can betransmitted to the ferrule 11 efficiently, uniformly, and reliably.

Another embodiment of the optical connector will now be explained. Asshown in FIG. 9, an optical connector plug 40 composed of a combinationof the ferrule 11 and the stopper 15 is constituted as one part of anoptical connector 39. The optical connector plug 40 shown in thisdrawing is utilized as a male optical connector plug of the opticalconnector 39, whereas a female optical connector plug 41 shown in FIG.16 exists as the other part of the optical connector 39. Namely, guidepins Pare secured to the male optical connector plug 40, whereas thefemale optical connector plug 41 is provided with guide pin insertionholes 9, whereby the optical connector plugs 40 and 41 differ from eachother in whether there are guide pins P or not. As a matter of course,the guide pins P having configurations similar to those in theabove-mentioned optical connector plug 2 are attached to the ferrule ofthe optical connector plug 40. For keeping the state of coupling betweenthe male optical connector plug 40 and the female optical connector plug41, a clip 43 having spring type pressing portions at both ends isutilized.

The guide pin P in accordance with the present invention is not limitedto the above-mentioned embodiments. For example, as shown in FIG. 17, inthe middle of a cylindrical inserting portion 31A, an engagement portion32 maybe formed, as a disk-shaped flange 33A, at a rear end portion ofthe guide pin P. Also, as shown in FIG. 18, continuously with acylindrical inserting portion 31B, an engagement portion 32 may beformed, as a cylindrical flange 33B, at the rear end portion of theguide pin P. Further, as shown in FIGS. 19 and 20, in the middle of acylindrical inserting portion 31C, an engagement portion 32 may beformed as triangular fins 33C.

INDUSTRIAL APPLICABILITY

The guide pin in accordance with the present invention facilitatessimplification of the structure, makes it possible to cut down the cost,and contributes to maintaining the quality of a ferrule. The opticalconnector plug in accordance with the present invention having a guidepin with such a configuration is similar thereto.

What is claimed is:
 1. An optical connector plug having: a ferrulehaving: a back face and a front face against which the other connectorplug is adapted to be abutted; and a guide insertion hole penetratingthere through from said front face to said back face; a ferrule housinghaving a ferrule accommodating space at a front end portion thereof; aguide pin having an inserting portion penetrating through said ferrulefrom said back face to said front face, and an engaging portion having adiameter greater than that of said guide pin insertion hole and beingadapted to abut against the back face of said ferrule, and a rear endportion of said inserting portion having a widened portion having awidth larger than the diameter of said guide pin insertion hole; aspring for pressing said ferrule outward in said ferrule accommodatingspace, for holding said ferrule in a floating state within said ferruleaccommodating space and for causing a tip portion of said guide pin toproject from said guide pin insertion hole; and a stopper disposedbetween said engaging portion and said spring member, said stopperabutting against a rear end face of said guide pin and said stopperbeing separated from said ferrule.
 2. An optical connector plugaccording to claim 1, wherein said stopper is formed with a depressionfor accommodating the rear end portion of said guide pin.
 3. An opticalconnector plug according to claim 1, wherein said stopper is formed witha depression for accommodating the rear end portion of said guide pin.4. An optical connector plug according to claim 1, wherein said guidepin has a protrusion projecting rearward from said engagement portion.5. An optical connector plug according to claim 1, wherein said guidepin has, between said inserting portion and said engagement portion, thewidened portion adapted to closely engage said guide pin insertion hole.6. An optical connector plug according to claim 1, wherein saidprotrusion projecting rearward from said engagement portion and thewidened portion adapted to closely engage said guide pin insertion holebetween said inserting portion and said engagement portion have a flatform.